Method using equalization data to determine defects in a cable plant

ABSTRACT

A method of estimating a defect location within a network is provided. Information of pre-equalization coefficients of an adaptive pre-equalizer of a terminal network element on the network is received. A total amount of equalization applied by a negative delay portion of the adaptive pre-equalizer relative to a main tap level and a total amount of equalization applied by a positive delay portion of the adaptive pre-equalizer relative to the main tap level is determined. The terminal network element is determined as being affected by a defect if at least one of the total amount of equalization applied by the negative or positive delay portions relative to the main tap level is at an unacceptable level. If a defect is identified, a location of the defect is estimated differently depending upon whether the negative or positive delay portion of the adaptive pre-equalizer applies the greatest amount of equalization.

BACKGROUND

Program providers such as multiple system operators, television networks and stations, cable TV operators, satellite TV operators, studios, wireless service providers, and Internet broadcasters/service providers, among others, require broadband communication systems to deliver programming and like content to consumers/subscribers over networks via digital or analog signals. Such networks and physical plants tend to be extensive and complex and therefore are difficult to manage and monitor for faults, impairments, maintenance issues and the like.

Monitoring network maintenance activities particularly presents problems to operators of extensive cable networks. For purposes of example, a cable network may include a headend which is connected to several nodes that may provide access to IP or ISPN networks. The cable network may also include a variety of cables such as coaxial cables, optical fiber cables, or a Hybrid Fiber/Coaxial (HFC) cable system which interconnect terminal network elements of subscribers to the headend in a tree and branch structure. The terminal network elements (media terminal adaptors (MTAs), cable modem, set top box, etc.) reside on the nodes which may be combined and serviced by common components at the headend.

Cable modems may support data connection to the Internet and other computer networks via the cable network. Thus, cable networks provide bi-directional communication systems in which data can be sent downstream from the headend to a subscriber and upstream from a subscriber to the headend. The headend typically interfaces with cable modems via a cable modem termination system (CMTS) which has several receivers. Each receiver of the CMTS may connect to numerous nodes which, in turn, may connect to numerous network elements, such as modems, media terminal adaptors (MTAs), set top boxes, terminal devices, customer premises equipment (CPE) or like devices of subscribers. A single receiver of the CMTS, for instance, may connect to several hundred or more network elements.

The conventional process for tracking which terminal devices are attached to which optical node and like information is a manual process. For instance, when a new customer's services are first enabled, a network operator may identify the specific node or location of the user and enter this information manually into a customer management database. This information can be valuable for resolving physical layer communications issues, performing periodic plant maintenance, and planning future service expansions. However, when the data is inaccurate or incomplete, it can lead to misdiagnosis of issues, excessive costs associated with maintenance, and prolonged new deployments. In addition, as communication traffic increases or new services are deployed, the need to understand loading of parts of the network becomes important, particularly if existing subscribers must be reallocated to different nodes or parts of the network.

Based on conventional practice, locating and identifying network and physical plant issues essentially relies upon the receipt of customer calls and manual technician analysis in response thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features of the embodiments described in the following detailed description can be more fully appreciated when considered with reference to the accompanying figures, wherein the same numbers refer to the same elements.

FIG. 1 is a snapshot screen view of a so-called dashboard of a graphical user interface according to an embodiment.

FIG. 2 is a view of a panel of the dashboard showing a cluster of objects displayed on top of a satellite image of a geographic area into which a network extends according to an embodiment.

FIG. 3 is a view of an interactive user interface display which may provide a starting point of the dashboard once a user logs into the system according to an embodiment.

FIG. 4 is a view similar to FIG. 3 with the map further zoomed-in to a particular region of the network service area according to an embodiment.

FIG. 5 is a view of an interactive user interface display which shows an alarm tree for use in investigating information of alarms shown on the display according to an embodiment.

FIG. 6 is a view similar to FIG. 5 with the alarm tree further expanded in accordance with an embodiment.

FIG. 7 is a view of a graphical user interface with a local geographic map showing a node location, terminal network elements, network path, and alarms in accordance with an embodiment.

FIG. 8 is a view of a graphical user interface similar to FIG. 7 with a cluster of terminal network elements highlighted based on geo-proximity in accordance with an embodiment.

FIG. 9 is a view of a graphical user interface similar to FIG. 8 that is displayed on a satellite image of the geographic area according to an embodiment.

FIG. 10 is a view of a graphical user interface similar to FIG. 9 and including a listing of alarms for the cable modems displayed on the map according to an embodiment.

FIG. 11 is a view of a graphical user interface similar to FIG. 10 and including a listing of a particular performance parameter (in this instance, downstream microreflections in dBs for absolute and delta values) for the cable modems displayed on the map and channels used thereby according to an embodiment.

FIG. 12 is a view of a wireless communication tablet having a display screen that may be used by a field technician in accordance with an embodiment.

FIG. 13 is a snapshot view of a display screen of the tablet providing a list of faulted modems in accordance with an embodiment.

FIG. 14 is a snapshot view of a display screen of the tablet providing the geographic locations of the faulted modems on a street map in accordance with an embodiment.

FIG. 15 is a schematic diagram of an adaptive pre-equalizer of a cable modem in accordance with an embodiment.

FIG. 16 is a view of a section of a network extending downstream from a node and in which cable modems subject to a group response defect are shown in accordance with an embodiment.

FIG. 17 is a view of a section of a network extending downstream from a node and in which cable modems subject to an echo response defect are shown in accordance with an embodiment.

FIG. 18 is a flowchart of a method of estimating a location of a defect in accordance with an embodiment.

DETAILED DESCRIPTION

For simplicity and illustrative purposes, the principles of embodiments are described by referring mainly to examples thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent however, to one of ordinary skill in the art, that the embodiments may be practiced without limitation to these specific details. In some instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the embodiments.

Embodiments disclosed herein are directed to automated management and monitoring systems, tools, and methods that enable issues occurring in a network, such as a cable network, to be proactively and automatically detected and located. The embodiments leverage a combination of key data and network topology such as information concerning the geographical location of an issue, the nature of the issue, and/or the severity of an issue to permit a network operator to quickly detect, isolate, locate and address problems. In addition, collection and analysis of historical, long term and periodic health information of a network provided by the embodiments can aid in determining trends that may indicate slow and steady degradation of a network element or component. Such degradation has conventionally remained undetected when relying only on manual spot checks by field technicians and only becomes detectable upon component failure.

According to embodiments, the above referenced tasks are accomplished automatically by a management and monitoring tool that is able to scale across extremely large networks thereby enabling network operators to become more proactive with network maintenance activities and to achieve higher levels of network availability and reliability. Operational costs can be reduced by decreasing the need for troubleshooting at a time after the occurrence of the problem or issue. In addition, the periodic collection and analysis of network conditions provides a view into critical network indicators and aids in resolving issues prior to customer impact.

Network monitoring can be performed such that information concerning geographic location of monitored network elements, such as cable modems or the like, and associated network component topology, such as HFC components and the like, are automatically populated into a network management database or the like for purposes of providing a visual display, such as a geographically accurate street map or satellite image of a region of a service area, that clearly indicates a fault or other issue and the geographical location thereof. Examples are provided by FIGS. 16 and 17. Thus, the path that the network takes geographically is displayed on the map along with the physical location of network elements and components within the network. Such a map provides a useful network management tool to network operators and field technicians for resolving issues in an efficient and prompt manner.

As one contemplated example, the map can be provided as part of a graphical interface which displays faults of varying severity levels ranging from critical to completely non-service affecting. Accordingly, in at least some embodiments, the severity of a fault on the network can be determined and displayed with the estimated geographic location of the fault on the map.

In addition, the network monitoring and management system or tool can be provided and fully integrated into software that is loaded and resides on a server or remote server connected to or communicating with the network. Of course, the software may reside on other devices and equipment such as equipment located at the headend of the network, cloud devices, and portable or mobile devices. Utilization of the software eliminates the need for manual analysis of data and permits large amounts of data to be automatically analyzed electronically by microprocessors or the like on a large scale.

The network management tool or software may estimate and make assumptions regarding probable tap and passive locations and couple this information with geo-encoded data and known optical node location data. From this cumulative information, the network management tool or software can estimate and automatically populate a map or the like of a given service area with monitored cable modem locations and associated network component topology. See FIGS. 16 and 17 for examples.

The geographic location of a fault and surrounding network path can be estimated, isolated, and displayed despite minimum information and manually entered data concerning the actual network path or network element location being available. The graphical interface can identify and display specific network elements as problematic. As an example, a network or HFC component such as cables, taps, passives, or the like that is identified as a suspect component potentially contributing to linear distortion, excessive loss impairments, or the like may be identified and displayed as a location of a fault. Whether a fault impacts a single subscriber or a group of subscribers may also be estimated and shown in the display.

Still further, the network management tool may be used to identify clusters or groups of network elements or cable modems that may share network or HFC infrastructure, such as common components including optics, nodes, amps, cables, taps, passives, and the like. In this regard, Management Information Base (MIB) information for service groups readily available via data pulls from a CMTS or like equipment at the headend of the network can be used in conjunction with the above referenced geographical location information. Network element groups or clusters can be readily displayed via the graphical interface and without the need for the software to reference other sources, perform testing, or wait for common impairment signature alarms to be raised.

Still further, the severity of a fault may be estimated with respect to upstream impairments through association of physical layer metrics including pre and post forward error correction (FEC) along with the number of impacted network elements or subscribers. Higher priority alarms can be assigned to groups of network elements or subscribers that exceed threshold values. In contrast, lower priority alarms can be assigned to faults such as detected for single network elements or subscribers.

According to an embodiment, the graphical interface referenced above may be presented in the form of a so-called “dashboard” to a user such as personnel of a network operations center. Critical alarms may be shown across the entire network in a geographical display of the network or parts thereof. In addition, access may be provided to statistics via use of the dashboard to allow the user to monitor the overall health of their network.

By way of example, various snap-shot views of a graphical user interface are provided in FIGS. 1-14. It should be understood that these displays are disclosed for purposes of example only and may be altered as desired.

A first example of a dashboard 10 which may be displayed to a user via a monitor or like electronic display screen is shown in FIG. 1. In this example, a first panel 12 of the dashboard 10 provides information of “Active Alarms” including a list of alarms or potential faults 14, a second panel 16 provides a so-called “Physical View” of the network, and a third panel 18 provides a geographically-accurate street map 20 showing the geographical location of the alarms listed in panel 12 along with the nearest node 22 or other network component. The map 20 may include roads and streets and names thereof. In addition, as best illustrated in FIG. 2, alarms can be overlaid on images 24, for instance satellite images, of the geographical service area in which the alarms are located.

When an issue, fault or alarm is identified, it can be associated and displayed with other issues, faults and alarms based on geographical proximity. For instance, see the alarms 14 within circle 26 in FIG. 1. This group or cluster of alarms provides a visual indicator of the network elements affected and can indicated a center point of a potential problem causing the cluster of alarms. For instance, see the center point 28 in FIG. 2. A user which selects the center point may be provided with a listing of problem network elements or modems. In addition, the cluster of alarms may have a single corresponding “alarm” object to thereby reduce the number of alarms displayed to the user.

After an issue is first identified by the network monitoring and management system, tool or software, the operator or user may be provided with several options to further investigate the apparent problem or problems. For instance, network issues may be isolated by “serving group” or “geographic proximity” (i.e., clustering) and may be prioritized by severity based on the number of customers/subscribers affected and the extent to which faults are service-affecting. The network faults can be linked by the management software to a map interface which enables the fault to be connected to a physical location in the network.

FIGS. 3-11 provide further examples of views of a dashboard which may be displayed to a network operator. Any type or number of available charts, maps, or alert views can be viewed and organized in the dashboard. By way of example, the dashboard 30 shown in FIG. 3 may be configured as a starting point when a user first logs onto the network monitoring and management software or system. Here, a “zoomed-out” view of the network is initially provided to permit an overall view of the network, which may span a large geographic area. Data is collected and analyzed by the network monitoring and management tool to identify a type of fault or faults and the estimated geographic location of the fault(s) solely based on analysis of the data.

FIG. 3 provides an entire network view 32 based on a geographic format and provides an indication of so-called “hot-spots” 34 of alarms. A listing 36 of alarms can be provided in a panel 38 which can also indicate the severity and location of the hot-spots 34. Charts such as a FEC deltas/CMTS channel exceeding threshold chart 40, a Flap deltas/CMTS channel exceeding threshold chart 42, and a CMTS channel utilization threshold crossing chart 44 can be displayed in a panel 46 and correspond to the alarms shown in the listing 36. Of course, these charts provide just a few examples of possible charts. A further example of such a dashboard is shown in FIG. 4 which provides a display of a section of the map 48 in greater detail.

In FIG. 5, a dashboard is shown in which panel 50 provides information on network topology. Here, the topology is provided in a form of a so-called alarm tree which enables a user to gain further information with respect to more narrowly defined sections of the network. For example, the topology could list CMTSs (such as CMTS-1, CMTS-2, CMTS-3, CMTS-4, and CMTS-5). Further, the fiber nodes (i.e., FN-A and FN-B) can be shown for any of the CMTSs and a number of network elements associated with an alarm can be listed. As shown in FIG. 6, the panel 50 can also be expanded to show the number of network elements associated with alarms per severity of alarm (i.e., critical, major, and minor).

A more local view of a street map 52 is shown in FIG. 7. Here a single fiber node 54 of the network is shown as is the network path 56 extending from the node 54 to terminal network elements 58, such as cable modems, serviced via the node 54. The shade (or color, etc.) of the terminal networks elements 58 can be used to visually indicate an alarm on the map 52. For instance, terminal network element 58 a is shown in a dark shade (or a particularly color, such as red) which may indicate an alarm of critical severity whereas terminal network elements displayed in lighter shades (other colors, such as yellow) may indicate an alarm of a minor severity. This same map 52 can be further investigated as shown in FIG. 8 in which a geo-proximity cluster 60 is shown highlighted. The path 56 of the cable plant may be estimated and shown such as in FIGS. 7 and 8. If desired, the user of the management tool is able to adjust the path 56 or enter in any known network topology information into the management software or tool should the estimated path and view be inaccurate.

Another view similar to FIG. 7 is shown in the map 62 of FIG. 9. Here the street map 52 has been modified to show actual satellite imagery of the surrounding geographic area. The node 54, path 56, and terminal network elements 58 are overlaid on the satellite imagery as are the alarms and other network topology. For purposes of further investigating a potential network fault, the “cable modems” illustrated in FIG. 9 can be shown in a drop down window 64 such as shown in FIG. 10. Here the MAC address, power status, noise status, upstream reflection status, downstream reflection status, FEC status for each cable modem or terminal network element 58. Some of these cable modems and listed statuses have no alarms whereas others have alarms of “minor” severity while others have alarms of “critical” severity. FIG. 11 shows the ability of the tool to further investigate network issues. Here, measurements corresponding to downstream microreflections in dBs are listed (as absolute and delta values) are shown in a window 66 so that a user may view these or any other values that are or are not the subject of an alarm.

Accordingly, after a network operator center user views the above referenced dashboards and investigates alarms therewith, for instance as shown above, and has identified a particular issue that needs to be resolved, the network monitoring and management tool, software or system can be used to assist the user in sending an appropriate field technician to the correct geographical location. The user can also use the management tool or software to assess the urgency with respect to the need to resolve the issue.

The network monitoring and management system, tool or software can also be used by a service technician in the field. For example, the network monitoring and management software may be run on a remote server that is accessible by the technician such as via a secure wireless web interface. For instance, a mobile device, such as a portable, lap-top, notebook, or tablet computer, a smart phone, or the like may be used to obtain various views, information and maps as discussed above. Accordingly, provided information can be used for rapid, real-time debugging of field issues and provide geographic information, provide real-time monitoring of upstream and downstream performance metrics and error states, and permit a technician to see the interdependency of multiple issues. The above can reduce the need for the technician to access the inside of residences, reduce the number of calls the technician needs to make to the head-end, and enable the technician to update network topology information while in the field. For purposes of this disclosure, “real-time” includes a level of responsiveness that is sufficiently fast to provide meaningful data that reflects current or recent network conditions as well as a level of responsiveness that tolerates a degree of lateness or built-in delay.

By way of example, a tablet 70 is shown in FIGS. 12-14 that may be used by a field technician to connect to the network monitoring and management software. In FIG. 12, the technician is provided with a display 72 that includes an icon 74 for a list of the CMTSs, an icon 76 for network wide alerts, an icon 78 for scanning or uploading information into the system, and a settings icon 80. FIG. 13 shows a display 82 providing a tabular view of network devices 84 having faults, and FIG. 14 shows a display 86 showing the same network devices 84 in a geographical map-style platform with the closest fiber node 88 or like network component. All of the above provides helpful and useful information to the field technician.

Various methods can be used by the network monitoring and management system, software, and tool described above that enables fault determination, fault location, mapping of the network geographically, displaying of faults with and without network topology information, displaying a cluster of network elements impacted by the same fault, and the severity of the fault. For example, a combination of monitored parameters and network topology information can be used to identify the likely physical locations of cable network defects. This approach is able to be implemented in software utilizing numerical analysis. In addition, a combination of sub-algorithms can be used to locate a common network failure point even when several different and potentially, seemingly unrelated, issues are observed.

The physical location of a network fault may be estimated by receiving information electronically of a physical topology of a network. Examples are provided by the topology shown in FIGS. 16 and 17 discussed below. This information may be provided via data pulls of information concerning network components and geographic locations of the network components and terminal network elements and geographic locations of the terminal network elements. The existence of a network fault within the network can be automatically and electronically detected by monitoring one or more performance parameters transmitted via upstream communications from terminal network elements on the network.

An example of a performance parameter that can be analyzed is equalization coefficients of adaptive pre-equalizers of cable modems. A physical location of the network fault on the network may be estimated based on the performance parameter detected, the information of the physical topology of the network obtained, and the terminal network element or elements from which the at least one performance parameter was received that indicated the network fault. Thereafter, a list of network components that may require inspection and may provide a source of the network fault can be automatically generated based on analysis of the performance parameters. By way of example, the listed network components may include drop cables, taps, trunk cables, splitters, amplifiers, nodes, and like components.

For purposes of example, the network shown in FIGS. 16 and 17 may be a hybrid fiber-coaxial (HFC) network which interconnects terminal network elements, such as cable modems, to a headend (not shown) of the network having a cable modem termination system (CMTS) (not shown) via a tree and branch network structure. The upstream communications are herein defined as communications transmitted in a direction from the terminal network elements toward the headend.

A geographically-accurate map may be automatically and electronically populated with the geographic locations of network components to which a network fault is attributed, a geographic location of each the terminal network elements impacted by the network fault, and a diagnostic alarm identifying the network fault. The map may be displayable, for instance, with the use of geospatial software.

The following algorithms may be used to estimate the physical location of the fault. Data is automatically gathered in real time and/or with an acceptable amount of delay by the CMTS, a server, or other equipment from cable modems in use by subscribers in the network to locate issues within the cable plant. More specifically, equalization data can be gathered and analyzed to proactively and accurately identify defects and determine the location of defects in the cable plant. In this manner, issues within the cable plant may be identified before they become service affecting and noticeable by a subscriber. The equalization data may be analyzed across all of the cable modems in a network and used to identify a particular problem or defect and the physical location of the defect within the network

A particular algorithm uses pre-distortion coefficients within an adaptive pre-equalizer of the transmitter of the cable modem to perform defect assessment. An adaptive pre-equalizer is a circuit in a cable modem that pre-equalizes or pre-distorts upstream signals transmitted by the cable modem for purposes of compensating for channel response impairments. Essentially, the adaptive pre-equalizer creates a digital filter that has approximately an opposite complex frequency response of the channel through which a desired signal is to be transmitted. In this way, the transmitted signal is pre-corrected for plant imperfections and problems. Accordingly, the pre-distortion coefficients generated and used by the adaptive pre-equalizer can also be used to provide an accurate representation of issues within the cable plant as experienced by each individual cable modem attached to the network.

The pre-equalization coefficients of a cable modem are a set of complex coefficients, for instance, f₁ through f_(n) of an n-tap linear transversal filter structure 100 shown schematically in FIG. 15. As an example, the filter structure 100 could have twenty-four taps (i.e., n=24) thereby having coefficients f₁ through f₂₄. As stated above, the intent of the coefficients is to pre-distort the upstream signal such that the pre-distortion equals the approximate inverse of upstream path distortion so that, as the pre-distorted upstream signal travels through the network, it is corrected and arrives substantially free of distortion at the upstream receiver of the CMTS.

As best shown in FIG. 15, the filter structure 100 includes a main tap 102 (i.e., a zero delay tap), a set of negative delay taps 104, and a set of positive delay taps 106. The signal to be transmitted upstream by the cable modem, in an undistorted state as intended to be received by the CMTS, is input at the front end 108 of the negative delay taps 104, and the signal as pre-distorted by the filter structure 100 is output at the rear end 110 of the positive delay taps 106.

According to embodiments, the location of a defect is determined by a particular location algorithm that is selected based upon which group of taps (i.e., the set of negative delay taps 104 or the set of positive delay taps 106) the adaptive pre-equalizer is primarily using to pre-distort the upstream signal. Thus, the pre-equalizer coefficients are analyzed and a different defect location algorithm is selected and used depending upon whether correction is being applied primarily to the negative or positive filter taps.

By way of example, if the adaptive pre-equalizer is primarily correcting the upstream signal using the positive delay taps 106, then the most accurate fault location algorithm is selected as one that searches for the “epicenter” of the issue. In this case, a plurality of modems will have their coefficients queried and analyzed, and the most likely location for the defect will be determined to be the network elements that are closest to the most severely affected modem or modems, or to the network elements closest to the tap that have the most severely affected average value across the modems sharing that tap.

In contrast, if the adaptive pre-equalizer is primarily correcting using the negative delay taps 104, then the most accurate fault location algorithm will be one that searches for the “top” of the issue. In this case, a plurality of modems will have their coefficients queried and analyzed and the most likely location for the defect will be determined to be the common network elements that are closest to the fiber node within the tree and branch architecture of the cable plant. Highest priority is placed upon nodes and amplifiers within the topology, as these are the most likely sources for this type of defect.

For purposes of this disclosure, the terms “Composite EQ”, “Group Response”, and Echo Response” are used as defined below. The term “Composite EQ” refers to a measure of the total amount of equalization (104 and 106) being applied to the upstream signal being transmitted by the cable modem, relative to the main tap 102 level. The term “Group Response” refers to a measure of the total amount of equalization being applied by the negative delay portion 104 of the equalizer to the upstream signal being transmitted by the cable modem, relative to the main tap 102 level, and the term “Echo Response” refers to a measure of the total amount of equalization being applied by the positive delay portion 106 of the equalizer to the upstream signal being transmitted by the cable modem, relative to the main tap 102 level.

FIG. 16 provides an example of a Group Response issue. In FIG. 16, a plurality of cable modems 120 are shown connected in tree and branch architecture to a node 122 which connects to the headend (not shown) of the network. A number of modems 124 within the network have adaptive equalization coefficient settings revealing unacceptable Group Response levels (i.e., an unacceptable amount of equalization applied by the negative delay portion 104 of the equalizer to the upstream signal being transmitted by the cable modem, relative to the main tap 102 level). In this case, the most likely source of the issue is identified as being components common with all the affected cable modems 124 and being closer to the CMTS or node 122 (i.e. at the “top”) for all of the affected modems 124. As shown in FIG. 16, the estimated location of the defect is centered about a common upstream splitter 126 and amplifier 128 that are highlighted by the circle 130 shown in the display. With this type of defect, the issue is not necessarily adjacent or near the most severely affected modem 132.

FIG. 17 provides an example of an Echo Response issue. In FIG. 17, a plurality of cable modems 140 are shown connected in tree and branch architecture to a node 142 which connects to the headend (not shown) of the network. A number of modems 144 within the network have adaptive equalization coefficient settings revealing unacceptable Echo Response levels (i.e., an unacceptable amount of equalization applied by the positive delay portion 106 of the equalizer to the upstream signal being transmitted by the cable modem, relative to the main tap 102 level). In this case, the most likely source of the issue is identified as being centered around the most severely affected modem 146 and includes the closest network element 148 to the most severely affected modem 146 and network elements 150 and 152 adjacent to the closet network element 148. The epicenter of this issue may be based upon the single worst modem Echo Response value, or the average of each modem sharing a common tap. Accordingly, as shown in FIG. 17 with circle 154, the most likely fault location is the epicenter location including any of the network elements 148, 150 and 152.

FIG. 18 provides a flowchart of an automated method that can be used by a server, CMTS or like equipment to estimate the location of a defect in a network. The terminal network elements of at least a section of the network are queried for information of pre-equalization coefficients (see step 160), and information of pre-equalization coefficients generated and in use by adaptive pre-equalizers of the terminal network elements are received (see step 162) for analysis.

For each terminal network element queried, a total amount of equalization applied by a negative delay portion of an adaptive pre-equalizer relative to a main tap level of the adaptive pre-equalizer and a total amount of equalization applied by a positive delay portion of the adaptive pre-equalizer relative to the main tap level of the adaptive pre-equalizer can be determined (see step 164). Terminal network elements that may be affected by a defect are identified. For instance, if at least one of the total amount of equalization applied by the negative delay portion relative to the main tap level and the total amount of equalization applied by the positive delay portion relative to the main tap level is at an unacceptable level, the existence of a defect can be confirmed (see step 166).

After the existence of a defect is confirmed, a location of a defect within the network based on the information of pre-equalization coefficients is estimated such that the location estimated is different depending on which one of the negative delay portion and the positive delay portion is being used by the adaptive equalizers affected by the defect to apply the greatest amount of equalization (i.e., a group response or an echo response). See step 168. When the negative delay portion applies the greater amount of equalization (i.e., a group response) for a set of the plurality of terminal network elements identified as being affected by a defect, the location of the defect is estimated as being at least one network component that is within an upstream part of network paths of all of the set of terminal network elements affected by the defect and that is closest to the set of terminal network elements identified as being affected by the defect. See step 170. This refers to a position at the “top” of the set of terminal network elements (i.e., the “top” being the end closest to the node, CMTS or headend).

However, when the positive delay portion applies the greater amount of equalization (i.e., an echo response) for a set of terminal network elements identified as being affected by a defect, the location of the defect is estimated as including a network component closest to a single most-severely affected terminal network element of the set (see step 172) and can also include adjacent network components. As an alternative, the location of the echo response defect can be estimated as being a network component closest to a tap shared by terminal networks elements that in average are most-severely affected by the defect. See step 174.

The method may also include a step of obtaining information of a physical topology of the network and location of the terminal network elements on the network and a step of automatically populating a geographically-accurate map with a geographic location of a network component to which the defect is attributed and a geographic location of the terminal network elements identified as being affected by a defect. See step 176. As another option, the method can include a step of automatically generating a list of network components that require inspection after said estimating step. The location of a defect will typically correspond to a location of a network component such as drop cables, taps, trunk cables, splitters, amplifiers, and node components.

A signal processing electronic device, such as a server, remote server, CMTS or the like can run a software application to provide the above process steps and analysis. In addition, a non-transitory computer readable storage medium having computer program instructions stored thereon that, when executed by a processor, cause the processor to perform the above discussed operations can also be provided.

The above referenced signal processing electronic devices for carrying out the above methods can physically be provided on a circuit board or within another electronic device and can include various processors, microprocessors, controllers, chips, disk drives, and the like. It will be apparent to one of ordinary skill in the art the modules, processors, controllers, units, and the like may be implemented as electronic components, software, hardware or a combination of hardware and software.

While the principles of the invention have been described above in connection with specific networks, devices, apparatus, systems, and methods, it is to be clearly understood that this description is made only by way of example and not as limitation on the scope of the invention as defined in the appended claims. 

We claim:
 1. An automated method of estimating a location of a defect within a network, comprising the steps of: receiving information of pre-equalization coefficients generated and in use by an adaptive pre-equalizer of a terminal network element on the network; determining from the information a total amount of equalization applied by a negative delay portion of the adaptive pre-equalizer relative to a main tap level of the adaptive pre-equalizer and a total amount of equalization applied by a positive delay portion of the adaptive pre-equalizer relative to the main tap level of the adaptive pre-equalizer; identifying the terminal network element as being affected by a defect if at least one of the total amount of equalization applied by the negative delay portion relative to the main tap level and the total amount of equalization applied by the positive delay portion relative to the main tap level is at an unacceptable level; and if the terminal network element is identified as being affected by a defect, estimating a location of a defect within the network based on the information of pre-equalization coefficients such that the location is estimated differently depending upon which one of the negative delay portion of the adaptive pre-equalizer and the positive delay portion of the adaptive pre-equalizer is being used to apply the greatest amount of equalization.
 2. The method according to claim 1, wherein said receiving, determining, and identifying steps are repeated for each of a plurality of terminal network elements on the network, and wherein the plurality of terminal network elements are connected to a headend of the network via a common node of the network via paths arranged in a tree and branch network structure.
 3. The method according to claim 2, wherein the network is a cable network, and wherein the headend has a cable modem termination system (CMTS) receiving pre-equalized upstream communications from the plurality of terminal network elements.
 4. The method according to claim 2, wherein, when the negative delay portion applies the greater amount of equalization for a set of the plurality of terminal network elements identified as being affected by a defect, the location of the defect is estimated as being at least one network component that is within an upstream part of the paths of all of the set of terminal network elements affected by the defect and that is closest to the set of terminal network elements identified as being affected by the defect.
 5. The method according to claim 2, wherein, when the positive delay portion applies the greater amount of equalization for a set of terminal network elements identified as being affected by a defect, the location of the defect is estimated as including a network component closest to a single most-severely affected terminal network element of the set.
 6. The method according to claim 5, wherein the location of the defect is estimated as including any additional network component that is adjacent to the network component closest to the single most-severely affected terminal network element.
 7. The method according to claim 2, wherein, when the positive delay portion applies the greater amount of equalization for a set of terminal network elements identified as being affected by a defect, the location of the defect is estimated as being a network component closest to a tap shared by terminal networks elements that in average are most-severely affected by the defect.
 8. The method according to claim 7, wherein the location of the defect is estimated as including any additional network component that is adjacent to the network component closest to the tap shared by the terminal networks elements that in average are most-severely affected by the defect.
 9. The method according to claim 2, further comprising the step of automatically populating a geographically-accurate map with a geographic location of a network component to which a defect is attributed and a geographic location of the terminal network elements identified as being affected by a defect.
 10. The method according to claim 1, further comprising the step of querying the terminal network element for the information of pre-equalization coefficients.
 11. The method according to claim 1, further comprising the step of automatically generating a list of network components that require inspection after said estimating step.
 12. The method according to claim 1, further comprising the step of obtaining information of a physical topology of the network and location of the terminal network element on the network.
 13. A method according to claim 1, wherein the location of a defect corresponds to a location of a network component, and wherein the network component is selected from a group consisting of drop cables, taps, trunk cables, splitters, amplifiers, and node components.
 14. The method according to claim 1, wherein the network is a hybrid fiber-coaxial (HFC) network, and wherein the terminal network elements include cable modems.
 15. A signal processing electronic device for automatically estimating a location of a defect within a network, comprising at least one processing unit configured to receive information of pre-equalization coefficients generated and in use by an adaptive pre-equalizer of a terminal network element on the network, determine from the information a total amount of equalization applied by a negative delay portion of the adaptive pre-equalizer relative to a main tap level of the adaptive pre-equalizer and a total amount of equalization applied by a positive delay portion of the adaptive pre-equalizer relative to the main tap level of the adaptive pre-equalizer, and identify the terminal network element as being affected by a defect if at least one of the total amount of equalization applied by the negative delay portion relative to the main tap level and the total amount of equalization applied by the positive delay portion relative to the main tap level is at an unacceptable level, and if the terminal network element is identified as being affected by a defect, said at least one processing unit being configured to estimate a location of a defect within the network based on the information of pre-equalization coefficients such that the location is estimated differently depending upon which one of the negative delay portion of the adaptive pre-equalizer and the positive delay portion of the adaptive pre-equalizer is being used to apply the greatest amount of equalization.
 16. A signal processing electronic device according to claim 15, wherein the signal processing electronic device is a server connected to the network, wherein the at least one processing unit is configured to receive information of pre-equalization coefficients generated and in use by a plurality of adaptive pre-equalizers of a plurality of terminal network elements on the network, and wherein the plurality of terminal network elements are connected to a headend of the network via a common node of the network via paths arranged in a tree and branch network structure.
 17. A signal processing electronic device according to claim 16, wherein, when the negative delay portion applies the greater amount of equalization for a set of the plurality of terminal network elements identified as being affected by a defect, the at least one processing unit is configured to estimate the location of the defect as being at least one network component that is within an upstream part of the paths of all of the set of terminal network elements affected by the defect and that is closest to the set of terminal network elements identified as being affected by the defect.
 18. A signal processing electronic device according to claim 16, wherein, when the positive delay portion applies the greater amount of equalization for a set of terminal network elements identified as being affected by a defect, the at least one processing unit is configured to estimate the location of the defect as including a network component closest to a single most-severely affected terminal network element of the set.
 19. A signal processing electronic device according to claim 16, wherein, when the positive delay portion applies the greater amount of equalization for a set of terminal network elements identified as being affected by a defect, the at least one processing unit is configured to estimate the location of the defect as being a network component closest to a tap shared by terminal networks elements that in average are most-severely affected by the defect.
 20. At least one non-transitory computer readable storage medium having computer program instructions stored thereon that, when executed by at least one processor, cause the at least one processor to perform the following operations: receive information of pre-equalization coefficients generated and in use by an adaptive pre-equalizer of a terminal network element on the network; determine from the information a total amount of equalization applied by a negative delay portion of the adaptive pre-equalizer relative to a main tap level of the adaptive pre-equalizer and a total amount of equalization applied by a positive delay portion of the adaptive pre-equalizer relative to the main tap level of the adaptive pre-equalizer; identify the terminal network element as being affected by a defect if at least one of the total amount of equalization applied by the negative delay portion relative to the main tap level and the total amount of equalization applied by the positive delay portion relative to the main tap level is at an unacceptable level; and if the terminal network element is identified as being affected by a defect, estimate a location of a defect within the network based on the information of pre-equalization coefficients such that the location is estimated differently depending upon which one of the negative delay portion of the adaptive pre-equalizer and the positive delay portion of the adaptive pre-equalizer is being used to apply the greatest amount of equalization. 